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Aug. 2, 1955 C. A. MENDENHALL STARTER GEARING FOR INTERNAL COMBUSTION ENGINES .gliggligu luillnliull" .Q\ Illlllllllllllllllllll Filed Nov. 12, 1955 VIT "lll 1| HIV IN VEN TOR. @www a. www

T RNE Y United States Patent STARTER GEABIN@ Foa INTERNAL.

Charles A. .Mendenhalh Horseheads, N; Yt, assignor to Be'ndirr` Aviation Corpcitation,` fcporation of Delaware Application November 12, 1953, Serial No. 321,403-

Tho nrt-#soot ioyootoa relatos to Starter soaring for intotoaljoombaotioa o ogooo aad more Paftio'olorlyi to a hoayy, duty Startet dryor, o. the aotootatoally trayofsins. tyro-` It io, an obioot of the Ptoooatr invention to Proyido o noi/ol. dfiyo of. thiol typo yyhoh moiotoilto its moshioe oosasomontwith tho oaiao to oo Started; ootil thooosino is reliably self-operative;

It is aaothor obioot to atoyitio, oooh a. doyioo io Whioh the` partsto be traversedhave a relatively "high polar momoot of: inertia. yylaiohiaootoo 'otiofoototy fooohiog otiaratoti, i. .'oyon. onder; ooyotsofoolioitiona `lt is another object to provide such a device including means for enforcing mesh of the gearing in case of toot-fi abutment. yyhoh operata otootiyolr, with @minimum of impact or shocl loads'. J

It is another object to` provide such a device having a. clutoh oonnootioa to tha aoryortstaatt Whiolov dritto `positively and overruns freely and quietly when the engine starts.

lt is another object to provide such a device in which the control of the overrunning clutch is entirely free from, and independent of, the mesh enforcing means.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation partly broken away and in section, of a preferred embodiment of the invention showing the parts in normal or idle position;

Fig. 2 is a view similar to Fig. 1 showing the parts in cranking position; and

Fig. 3 is a similar view showing the parts in the positions assumed when the engine starts and causes the driving pinion to overrun the starting motor.

In Fig. 1 of the drawing there is illustrated a power shaft 1 which may be the extended armature shaft of a starting motor not illustrated, or may be coupled to the armature shaft 2 by any suitable means as illustrated. The power shaft is provided on one end with an enlargement 3 forming a driving head having overrunning clutch teeth 4 formed thereon. A hollow screw shaft 5 is slidably journaled on the power shaft and is provided with clutch teeth 6 which mate with the teeth 4 on the driving head 3 for transmission positively of cranking torque from the power shaft to the screw shaft.

An abutment ring 7 is mounted on the power shaft and bears against a split thrust ring 8 which is seated in a groove 9 in the power shaft and occupies a counterbore 10 in the abutment ring 7 whereby the lock ring is confined in its seat. A thrust washer 11 is loosely mounted on the power shaft between the screw shaft 5 and the abutment ring 7, and a light compression spring in the form of a dished split washer 12 located between the thrust washer 11 and the abutment ring 7 serves to urge the clutch teeth 6 into engagement with the teeth 4 on the driving head 3. The abutment ring 7 is provided with a second counterbore 13 which houses the spring 12 2,714,312 EatferltedA Aug. 2, 1955 2 when the thrust washer 1 1 is pressed against the abutment.

A pinion 14 is slidably journaledI on the power shaft 1 for movement into and out of engagement with a gear 15A on the engine to be started. Means for actuating the pinion from the screw shaft 5 is provided comprising a control nut 16 which is threaded on the screw shaft, and a" barrel member `17 surrounding the control nut and having at one end a splined connection 18 to saidpinion. In order to transmit rotation fromV the control nut` to thebarrel, the control nut is formed at one end wi'h a radial flange 19, and a plurality of friction discs 21V, 22 arel splined alternately to the barrel and control nut andI are compressedl between the llange 19 of the control nut anda thrust ring 23 which is urged toward the flange 19 by a plurality of compression springs 24 bearing against an adjustment abutment 25 threaded on the control nut.

Hub 26 of the pinion which is splined within the end of; the barrel 1` 7 is retained in the barrel by means of a thrust ringV 27 and a lock ring 28 seated in the end of the pinion, hub. Means for normally holding the pinion 14 in extended relation to the barrel is provided in the form of a mesh-enforcing spring 29 located in the barrel between the thrust ring'27 and a spacing thirnbleI 31 which bears against the end of the control nut. The reaction of themeslrenforcing spring 29 is taken by a lock ring 32 seatedin the freeend of the barrel 117 andy forming 4a retaining abutment for the thrust ring 23 of the frictipn coupling 2 1, 212. p

Means: for holding the pinion 14 in engagement with the engine gear 15 until the engine has been successfully started,Y is'p'royided' in the form off a detent member 33` slidably mounted in a radial bore in the flange 19 of the control nut, and yieldably pressed against the periphery of the screw shaft by a spring 34. The screw shaft has a notch 35 in position to receive the detent 33 when the pinion 14 is meshed with the engine gear 15. The notch terminates in a shoulder 36 which engages the detent 33 upon initiation of the demeshing movement of the control nut and resists such movement until the detent is withdrawn by centrifugal force caused by the rapid rotation of the pinion and barrel assembly when the engine starts. ln order to yieldably hold the parts in idle position, the screw shaft 5 is formed with an inclined shoulder or ramp 37 which cooperates with the detent 33 to prevent the pinion from drifting toward the engine gear 15 due to vibration while the engine is in operation.

In operation, starting with the parts in the positions shown in Fig. 1, rotation of the power shaft 1 in the direction of the arrow is transmitted to the screw shaft 5 through the clutch teeth 4, 6, whereby the control nut 16 is threaded along the screw shaft, moving the pinion 14 into mesh with the engine gear 15, the fully meshed position being defined by the abutment ring 7 which arrests the movement of the control nut as shown in Fig. 2. At this time the screw shaft 5 is forced against the driving head 3 by the screw-jack action of the control nut, thus firmly compressing the overrunning clutch teeth 6, 4 for positive transmission of torque.

If, during the meshing movement, tooth abutment should occur between the pinion and the gear, the longitudinal movement of the pinion is momentarily arrested,

but the meshing movement of the barrel 17 continues as permitted by the splined connection 18, under the control of the mesh-enforcing spring 29. Torque is thus yieldably applied to the pinion 14 to index it into proper registry to enforce mesh, there will be only a very slight impact involved, and vmeshing will in all cases proceed quietly and without injury to the gear teeth.

When the control nut 16 is arrested by the abutment ring 7, the consequent transmission of torque from the motor to the engine gear is cushioned by the overload slip coupling 21, 22 which thus absorbs the peak torque and protects the parts against overload.

When the engine starts, the pinion and barrel assembly are accelerated by the engine gear, causing the control nut to thread itself back on the screw shaft until the detent 33 engages the shoulder 36. This movement is sutiicient to permit the screw shaft 5 to move to the right against the action of the clutch spring 12, allowing the clutch teeth 6, 4, to discharge and permit the screw shaft to overrun the power shaft as shown in Fig. 3.

When the rotation of the overrunning parts is sufficiently rapid to withdraw the detent 33 by centrifugal force the parts are permitted to return to their idle position.

Although but one form of the invention has been shown and described in detail, it will be understood that other embodiments are possible and that changes may be made in the precise form and arrangement of the parts without departing from the spirit of the invention.

I claim: K

1. In an engine starter drive a power shaft, a screw shaft slidably journalled thereon and having a dental overrunning clutch connection therewith, an abutment on the power shaft limiting declutchng movement of the screw shaft thereon, a light compression Spring between the screw shaft and said abutment tending to close the clutch; a pinion slidably journaled on the power shaft for movement into and out of mesh with a gear of the engine to be started, a control nut threaded on the screw shaft, a barrel member surrounding the control l nut and having a splined connection at one end with the pinion, means limiting the relative longitudinal movement of the barrel and pinion, means including a compression spring normally keeping the pinion in extended relation to the barrel, and means including an overload slip coupling for transmitting rotary and longitudinal movement from the control nut to the barrel.

2. An engine starter drive as set forth in claim l including further a centrifugally movable detent in the control nut bearing on the screw shaft and said screw shaft having a peripheral abutment so positioned as to engage the detent and oppose demeshing movement of the control nut until the detent is withdrawn by centrifugal force. A

3. A starter drive as set forth inclaim l in which said abutment is in the form of a ring seated on the power shaft, and including further a thrust washer between the end of the screw shaft and the overrunning clutch spring and forming a thrust bearingA between the control Vnut and abutment ring,r said abutment ring having a counterbore on both sides, one counter-bore serving Vto house the overrunning clutch spring;y said power shaft having a peripheralr groove for defining the position of the abutment ring thereon, and a split thrust ring in the groove seated in the corresponding counterbore .of the abutment ring. f v v 4. A starter drive as set forth in claim 1 in which the overload'slip coupling comprises an assembly of a plurality of rings splined alternately to the barrel and control lnut, and adjustable spring means onthe control nut for compressing said assembly.

References Cited in the file of this patent UNITED STATES PATENTS 2,620,671 'Digby Dec. 9, 1952 

